Antiphospholipid syndrome in rural, remote, and First Nations peoples in the Top End of the Northern Territory, Australia

Background: The Northern Territory of Australia has a high proportion of First Nations peoples living in remote communities and a high burden of chronic autoimmune diseases. The epidemiology and clinical outcomes of antiphospholipid syndrome (APS) in First Nations Australians are poorly characterized. Objectives: To determine the epidemiology, presenting features, and outcomes of patients with APS using an 18-year retrospective cohort of newly diagnosed patients presenting to Royal Darwin Hospital (2002-2020). Methods: Patients admitted to Royal Darwin Hospital with a new incident diagnosis of APS between January 2002 and December 2020 were identified and followed until December 2022, with data on baseline demographics, clinical and laboratory features, and overall survival extracted from electronic and paper medical records. Results: Fifty-three patients with APS were included, of whom 40 (75%) were First Nations and 46 (87%) were female. Thirty (75%) of First Nations patients with APS resided in very remote Australia vs 0 (0%) non-First Nations patients. Eighteen cases (34%) had primary APS, and 35 cases (66%) had secondary APS, most in association with lupus. Eight (15%) cases developed catastrophic APS (CAPS), all in First Nations patients. There were 13 deaths (of which 11 were among First Nations patients). Patients with CAPS had significantly shorter median overall survival (8.3 years from diagnosis), with median survival in non-CAPS patients not reached (P = .003). Conclusion: There is a high prevalence of APS in First Nations patients living in very remote Australia admitted for tertiary care in the tropical north of the Northern Territory, Australia. The rate of CAPS in First Nations patients was high, and CAPS was associated with significantly shorter survival. Larger prospective studies are required to inform improved models of care for First Nations and remote Australians living with APS.